Microscopic polymer armour could allow researchers to develop effective and environmentally friendly anti-fouling coatings for ships and oil rigs, and prevent rejection of surgical implants.
The armour, developed by the US government’s Pacific Northwest National Laboratory (PNNL) in Richland, Washington, encases and protects enzymes, keeping them active for long periods.
Enzymes are long, intricately-folded proteins which act as natural catalysts, cleaving some chemical bonds and creating others. unlike many synthetic processes, they do it without organic solvents or toxic chemicals.
Chemical engineers are increasingly trying to use enzymes in industrial processes. but enzymes retain their activity for only a few hours. The PNNL team, led by Jungbae Kim and Jay Grate, claim that the armour can enclose a single enzyme, creating a single enzyme nanoparticle (SEN) which can stay active for up to five months.
Possible applications include clean-up of contaminated soil or toxic waste, where a single treatment could last for months. They could also be used to disrupt the formation of the polymer glues with which barnacles attach themselves to ships’ hulls and the support legs of oil rigs, and to prevent the formation of protein plaques on medical implants.
Kim and Grate started with an enzyme called alpha-chymotrypsin, which cleaves certain proteins. In a series of chemical reactions, they added hydroxy groups to the enzyme’s surface, making it soluble in water; then added compounds containing vinyl groups, which grew into short threads of PVC sticking out of the enzyme surface.
A third reaction formed cross-links between these chains made from a silicon-containing compound. The links formed a layer like a basketball net across the molecule’s surface, which allowed the enzyme to retain its protein-splitting activity, but prevented it breaking down. ‘Converting free enzymes into these enzyme-containing nanoparticles results in more stable catalytic activity,’ said Grate.